Apparatus for the continuous lixiviation of comminuted, particularly vegetable or animal material



Feb. 15, 1966 SIBBERSEN 3,235,338

APPARATUS FOR THE CONTINUOUS LIXIVIATION OF COMMINUTED, PARTICULARLY VEGETABLE OR ANIMAL MATERIAL Filed June 27, 1962 50!. I0 SUPPL V SOLVE/VT //VL7' SON [N7 OUTLET INVENTOR D. D. JLbZrei-sen v ATTORNEYS ite States This invention relates to an apparatus for the continuous lixiviation of disintegrated or comminuted par ticularly vegetable or animal material, comprising an inclined trough provided at its lower end with a supply chute for the said material and containing a plurality of helical conveyors rotatable about axes parallel to each other and to the generating line of the trough wall and constructed with passage openings for the lixiviation liquid, said conveyors in axial projection filling substantially the full cross section of the trough.

In the known apparatuses of this kind, the axes of the screw conveyors are located substantially horizontally side by side. By this arrangement, in general, a very satisfactory feeding of the material is obtained, because the use of a plurality of the screw conveyors located side by side prevents the material from being taken along by the screw conveyors in a pure rotational movement instead of being fed forward. Thereby it becomes superfluous to provide stationary breaker bars, such as are necessary in apparatuses with only one screw conveyor.

However, the known apparatuses with a plurality of screw conveyors have certain limitations to their function which are of some disadvantage in practical operation. First, it is absolutely necessary for the operation of the apparatus that the material fills the cross section of the trough practically completely, because otherwise no, even moderately well defined and uniformly compressed body of liquid penetrable material may be formed. A further consequence of this is that there is practically no other possibility of varying the capacity of the apparatus than varying the speed of rotation of the screws, and this is only feasible within certain limits, because the time of travel of the material from one end of the trough to the other, and thereby the time in which it is subjected to lixiviation, will otherwise vary too much. In practice it has been found that the lower limit of the capacity of such an apparatus amounts to about 70% of the nominal capacity. However, it may frequently be desirable to be able to go down to a considerably lower capacity.

Another limitation of the adaptibility of the known apparatuses is to be seen in the fact that if the outer diameter of the screw (or screws) is increased beyond a certain limit, the friction between the helical blades and the material is so considerably increased that the required driving power increases out of proportion to the quantity of material conveyed. In practice, this puts a limit to the maximum capacity obtainable per screw, and if it is attempted to increase the capacity by increasing the number of screws, the difiiculty is encountered that the trough becomes so wide that it will be very complicated and practically impossible to obtain uniform distribution of the material over the whole width, apart from the fact that such a trough occupies a very large floor space.

It is the object of the invention to remedy the drawbacks described, and with this object in view, the principal characteristic of the invention is that the axes of the helical conveyors are located in pairs vertically or atent O 3,235,338 Patented Feb. 15, 1966 substantially vertically above one another at a mutual distance substantially equal to and at any rate not exceeding the sum of the radii of the outer contours of the two helical conveyors, the trough wall being shaped substantially to match the combined contour of the helical conveyors.

An apparatus constructed in this manner is capable of satisfactory operation as soon as the cross sectional zone of the trough covered by the lower screw conveyor (or conveyors) is filled with material, i.e. a satisfactory, uniform lixiviation may be obtained even if the upper screw conveyor (or conveyors) runs completely or partly idle. Hereby it is possible to obtain a much greater range of variation of the capacity than with the known apparatuses, eg as follows: At minimum capacity only the lower screw conveyor (or conveyors) is in operation, and at the minimum speed of rotation permissible for said screw conveyor, whereafter the capacity may be increased to a certain limit by increasing the speed of rotation. When it is not possible to go any further in this manner, the upper screw conveyor (or conveyors) may be put in operation, too, and this may then, if desired, also be completely filled, the speed of rotation being again reduced to the minimum value, and the number of revolutions being subsequently increased gradually as the capacity requirements increase. In practice it has been found that in this manner it is possible to control the capacity as far down as to 30% of the nominal capacity.

To obtain the advantage described, it is important that no dead zones should be formed between the screw conveyors of each pair, which is obtained by the mutual arrangement of the screw conveyors and the shaping of the trough wall specified above. Preferably, the screw conveyors of each pair, located one above the other, should interengage slightly. A more pronounced interengagement is not necessary in order to secure a satisfactory feeding, and would therefore only result in an unnecessary increase of the friction between the material and the helical windings and an unnecessary stirring of the material whereby it would also be more difficult to carry out feeding by the lower screw conveyor (or conveyors) alone without disturbances occurring from the upper screw conveyor (or conveyors).

It was assumed above that when the upper screw conveyors are taken into use in addition to the lower screw conveyors, the cross sectional area of the upper screw conveyor-s is completely filled, such as is necessary in the case of screw conveyors in one level only. It has been found, however, that a complete filling of the upper screw conveyors is not absolutely necessary, because the upper screw conveyors will have a smoothing effect on the surface of the material present in the zone above the lower screw conveyors such that a satisfactory, uni form lixiviation is obtained even if the zone of the upper screw conveyors is only partly filled. Hereby, an additional flexibility in the adaptation of the capacity of the apparatus to the requirements in each individual case is obtained.

Since the material supplied to the apparatus has a natural tendency to remain on the surface of the lixiviation liquid and consequently to be conveyed by the upper screw conveyor (or conveyors), it is proposed, according to the invention, in order to obtain the best possible utilization of the apparatus, to construct the supply chute, at least at its lower end, with separate supply paths for the supply of comminuted material to the zones of the upper and the lower helical conveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movement produced by the gravity of the material. Owing to this arrangement, the material will be supplied predominantly to the lower screw conveyor (or conveyors) and will begin to fill the zone of the upper screw conveyor only when the zone of the lower screw conveyor has already been completely filled.

In a preferred embodiment of the invention, to obtain this forced distribution of the supply of material, a guide plate is provided at the lower end of the chute, said guide plate extending downwards at an inclination in the feeding direction from a transverse line in the zone of the chute to a portion of the shaft of the upper helical conveyor constructed without helical windings. By virtue of this arrangement, no special driving mean-s need be added for supplying material to the zone of the lower screw conveyor (or conveyors) seeing that the rearmost part of the upper screw conveyor (or conveyors), viz. the zone located behind the said portion devoid of helical windings, can be used for the said purpose.

Moreover, according to the invention, the lower screw of each pair and the upper screw of the same pair, or at least the section of the latter screw located beyond the guide plate, may have the same directions of rotation. By so selecting the directions of rotation, the upper screw conveyor (or conveyors) will contribute to a particularly great extent to the above mentioned smoothing of the surface of the filling of material under the operating condition where the zone of the upper screw conveyor (or conveyors) is only partly filled.

If the apparatus has two or more pairs of screw conveyors located vertically above one another, the distance between the planes of the axes of any two adjacent pairs of screw conveyors may, according to the invention, advantageously be smaller than the sum of the radii of the outer contours, as viewed in axial projection, of the two juxtaposed screw conveyors, while at the same time the two pairs of screws have winding-s of opposite pitch and opposite directions of rotation. Hereby the best possible feeding of the material in a uniform manner and in a uniformly packed state is obtained in each of the screw conveyor levels.

In order to eliminate the danger of the accumulation of material under the guide plate in the process of being fed to the lower screw conveyors, the section of the upper screw conveyor of each pair located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, may, according to the invention, be terminated by a conical screw tapering towards the guide plate. For certain materials it may be advantageous, according to the invention, in order to obtain proper feeding of material to the lower screw conveyor (or conveyors), to construct the section of the upper screw conveyor (or conveyors) located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, with a pitch different from that of the section of the same screw conveyor (or conveyors) located beyond the guide plate.

A further possibility of controlling the relative proportion of the feeding of material to the lower and the upper screw conveyors, may be obtained, according to the invention, by so arranging the apparatus that the direction of rotation and the speed of rotation of the section of the upper screw conveyor of each pair of screws located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, are independent of the direction of rotation and the speed of rotation, respectively, of the section of the same screw conveyor lo cated beyond the guide plate.

According to the invention, substantially prismatic filling bodies may be provided between adjacent pairs of screw conveyors at the level of the borderline between the zones of operation of the upper and lower screw conveyors, respectively. By this arrangement, the danger of the formation of a dead zone without any feeding action at the position referred to is eliminated and, according to the invention, the filling bodies may also be rendered useful by being provided with heating or cooling means, e.g. by being hollow and provided with inlets and outlets for a heating or cooling medium. In both cases, a particularly eflicient exchange of heat will be obtained because this exchange takes place in the interior of the material being fed so that it is not necessary, as in the known apparatuses, to limit the heat exchange to the circumferential surface.

In order to facilitate the distribution of the material between the upper and the lower screw conveyors, a partition may, according to the invention, be provided in the supply chute, said partition extending upwards from the guide plate substantially at right angles to the axes of the screw conveyors, and, according to a special embodiment of the invention, the said partition, or part of same, may form a closure for the supply chute to the upper screw conveyors, located above the guide plate, said closure being rotatable about an axis extending transversely of the trough about or at the level of the upper edge of the said guide plate. Hereby it becomes possible to completely stop the supply of material to the upper screws in case the apparatus is to operate at a capacity so low that only the zone of the lower screws is to be filled.

One embodiment of an apparatus according to the invention is illustrated in the drawing in which FIG. 1 shows a longitudinal vertical section through the apparatus,

FIG. 2 a cross section along the line II-1I in FIG. 1, and

FIG. 3 is a diagrammatic view showing the prismatic body.

In the drawing, 1 is a slightly inclined trough-shaped container, to the lower end of which a supply chute 2 is connected. Two pairs of screw conveyors 3, 3a and 4, 4a are provided in the trough. The axes 5, 5a and 6, 6a of the two screws of each pair 3, 3a and 4, 4a, respectively, are located vertically above one another. The two upper screw conveyors 3a and 4a are located horizontally side by side, as viewed in cross section, and the same applies to the two lower screw conveyors 3 and 4. The two screws of each pair interengage slightly only whereas considerable engagement exists between each two screws located horizontally side by side. The outer contour of the trough matches the outer contour of the four screws at the bottom and on the side.

Preferably the lower screw B or 4 of each pair and the upper screw 3a and 4a respectively of the same pair have the same directions of rotation while the two pairs of screws 3, 3a and 4, 411, respectively, have windings of opposite pitch and opposite directions of rotation as indicated by arrows in FIG. 2.

The shafts of both the upper and the lower screws extend rearwardly into the zone under the chute 2. In the chute a partition 7 is provided which extends substantially at right angles to the shafts of the screw conveyors and from the lower edge of which an inclined guide plate 8 extends downwards to a section 9 of the shafts of the upper screw conveyors where no screw blades are provided. Behind this guide plate, the upper screws are terminated with conical screw blades 10. Thereby these screw blades urge the material supplied to them forwards against the underside of the guide plate 8 whereby the material is caused to slide along the guide plate to the zone of the lower screws. Owing to the conical shape of the screw blades 10, the operating zone of the latter is extended to the immediate neighbourhood of the guide plates so that a movement is imparted to the material along the guide plate whereby there will be no danger of the accumulation of material.

The conical screw blades 10 may be rigidly attached to the shafts 5a and 6a or they may be rotatably mounted thereon and provided with driving means of their own. In the latter case they may be rotated at a difierent speed from or even in the opposite sense than the main portions of the screw conveyors 3a and 4a. In this manner the feeding of material to the upper screw conveyors may at will be accelerated or retarded relative to the feeding of material to the lower screw conveyors in order to obtain optimum operating conditions. For the same purpose the screw blades may have a pitch different from that of the main portions of the screw conveyors 3a and 4a.

The part of the partition 7 above the upper edge of the guide plate 8 may, if desired, be rotatable to the right (as viewed in the drawing) so that the supply of material to the upper screws may be completely stopped.

In the free space between the four screws a substantially prismatic hollow filling body 11 is provided which may be constructed with an inlet and an outlet for a heating or cooling medium.

Besides, the apparatus is provided at its upper end with an inlet for the lixiviation medium, not shown, and with means, not shown either, for removing the lixiviated material, e.g. rotating conveyor blade-s, screws or bucket elevators, and at the lower end of the apparatus an outlet, not shown, for extract is provided.

The material tobe lixiviated is supplied to the container 1 through the chute 2 and is fed upwards through the inclined container 1 by means of the screw conveyors 3, 3a and 4, 4a and encounters the lixiviation medium supplied to the upper end of the container in counter current, the said lixiviation medium flowing substantially axially through the container under the influence of its gravity, the extract thereby formed encountering material with a constantly increasing content of extractable matter until the final extract is discharged from the zone where fresh disintegrated material is supplied.

In all other respect-s, the apparatus operates substan tially as previously described.

A lixiviation apparatus may, according to the invention be constructed in various ways. Instead of two pairs of screws it may e.g. be constructed with one pair of screws only, and it may also comprise more than two pairs of screws. It will be understood that, for a certain outer diameter of the screws and a certain total width of the trough, a doubling of the capacity may be obtained as compared with the known apparatuses in which screw blades are provided at one level only, and from this maximum capacity, a substantial reduction may be obtained by arranging for the feeding to be effected by the lower pair of screws only, while at the same time causing these to rotate at the minimum speed of rotation permissible.

The apparatus is primarily intended for the extraction of vegetable or animal material, but it is entirely possible to use it for other extraction or washing processes or e.g. for the chemical treatment of minerals with solutions.

I claim:

ll. An apparatus for the continuous lixiviation of disintegrated or comminuted, particularly vegetable or animal material, comprising a slightly inclined trough, a supply chute for supplying material to be lixiviated to the lower end of said trough, means for removing lixiviated material from the upper end of said trough, means for supplying a lixiviating liquid to the upper end of said trough, means for removing enriched lixiviating liquid finom the lower end of said trough, at least four helical conveyors of constant pitch mounted in said trough for rotation about axes parallel to each other and to the generating line of a wall of the trough, and having said passage openings for the lixiviating liquid, said conveyors in axial projection filling substantially the full cross section of the trough, the axes of the helical conveyors being located in pairs substantially vertically above one another at a mutual distance less than the sum of the radii of the outer contours of the two helical conveyors of each pair, and the trough wall being shaped substantially to match the combined contour of the helical conveyors.

2. An apparatus as in claim 1 in which the supply chute is constructed, at least at its lower end, with separate supply paths for the supply of comminuted mate- 6 rial to the zones of the upper and the lower helical coriveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movement produced by the gravity of the material.

3. An apparatus as in claim 1, in which the supply chute is constructed, at least at its lower end, with separate supply paths for the supply of comminuted material to the zones of the upper and the lower helical conveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movements produced by the gravity of the material, and in which a guide plate is provided at the lower end of the chute, said guide plate extending downwards at an inclination in the feeding direction from a transverse line in the zone of the chute to a portion of the shaft of the upper helical conveyor which is non-helical.

4. An apparatus as in claim 1, in which the supply chute is constructed, at least at its lower end, with separate supply paths for the supply of comminuted material to the zones of the upper and the lower helical conveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movements produced by the gravity of the material, and in which a guide plate is provided at the lower end of the chute, said guide plate extending down-wards at an inclination in the feeding direction from a transverse line in the zone of the chute to a portion of the shaft of the upper helical conveyor which is non-helical, and the section of the upper screw conveyor of each pair being located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, is terminated by a conical screw tapering towards the guide plate.

5. An apparatus as in claim 1, in which the supply chute is constructed, at least at its lower end, with separate supply paths for the supply of comminuted material to the zones of the upper and the lower helical conveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movements produced by the gravity of the material, and in which a guide plate is provided at the lower end of the chute, said guide plate extending downwards at an inclination in the feeding direction from a transverse line in the zone of the chute to a portion of the shaft of the upper helical conveyor which is non-helical, and the direction of rotation and the speed of rotation of the section of the upper screw conveyor of each pair of screws located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, are independent of the direction of rotation and the speed of rotation, respectively, of the section of the same screw conveyor located beyond the guide plate.

6. An apparatus as in claim 1, in which the supply chute is constructed, at least at its lower end, with separate supply paths for the supply of comminuted material to the zones of the upper and the lower helical conveyor respectively, the supply path to the lower zone containing feeding means for supplementing the feeding movements produced by the gravity of the material, and in which a guide plate is provided at the lower end of the chute, said guide plate extending downwards at an inclination in the feeding direction from a transverse line in the zone of the chute to a portion of the shaft of the upper helical conveyor which is non-helical, and the section of the upper screw conveyor located under the inclined guide plate and on the proximate side thereof, as viewed in the feeding direction, has a pitch different from that of the section of the same screw conveyor located beyond the guide plate.

7. An apparatus as in claim .1, having at least two pairs of screw conveyors located substantially vertically one above another, substantially prismatic bodies being provided between adjacent pairs of screw conveyors at the level of the borderline between the zones of operation of the upper and lower screw conveyors, respectively.

8. An apparatus as in claim 1, having at least two pairs of screw conveyors located substantially vertically one above another, substantially prismatic bodies being provided between adjacent pairs of screw conveyors at the level of the borderline between the zones of operation of the upper and lower screw conveyors, respectively, and the filling bodies are provided with conditioning means, and the filling bodies being hollow and are provided with inlets and outlets for a conditioning medium, the filling bodies being hollow and are provided with inlets and outlets for a conditioning medium.

References Cited by the Examiner Reinohl 23-267 6/1932 Schlotterhose 23-27O X 6/ 1940 Bonotto 23270 X 5/1950 Consalvo 1812 7/ 1955 Bruniche-Olsen 23-270 X 9/1963 Selbach 18-12 7/1964 Schaffer 23270 X FOREIGN PATENTS 11/ 1922 France.

9/ 1930 Germany.

3/1961 Great Britain.

NORMAN Y UDKOFF, Primary Examiner.

GEORGE D. MITCHELL, Examiner.

S. EMERY, M. H. SILVERSTEIN, Assistant Examiners. 

1. AN APPARATUS FOR THE CONTINUOUS LIXIVIATION OF DISINTEGRATED OR COMMINUTED, PARTICULARLY VEGTABLE OR ANIMAL MATERIAL, COMPRISING A SLIGHTLY INCLINED TROUGH, A SUPPLY CHUTE FOR SUPPLYING MATERIAL TO BE LIXIVIATED TO THE LOWER END OF SAID TROUGH, MEANS FOR REMOVING LIXIVIATED MATERIAL FROM THE UPPER END OF SAID TROUGH, MEANS FOR SUPPLYING A LIXIVIATING LIQUID TO THE UPPER END OF SAID TROUGH, MEANS FOR REMOVING ENRICHED LIXIVIATING LIQUID FROM THE LOWER END OF SAID TROUGH, AT LEAST FOUR HELICAL CONVEYORS OF CONSTANT PITCH MOUNTED IN SAID TROUGH FOR ROTATION ABOUT AXES PARALLEL TO EACH OTHER AND TO THE GENERATING LINE OF A WALL OF THE TROUGH, AND HAVING SAID PASSAGE OPENINGS FOR THE LIXIVITING LIQUID, SAID CONVEYORS IN AXIAL PROJECTION FILLING SUBSTANTIALLY THE FULL CROSS SECTION OF THE TROUGH, THE AXES OF THE HELICAL CONVEYORS BEING LOCATED IN PAIRS SUBSTANTIALLY VERTICALLY ABOVE ONE ANOTHER AT A MUTUAL DISTANCE LESS THAN THE SUM OF THE RADII OF THE OUTER CONTOURS OF THE TWO HELICAL CONVEYORS OF EACH PAIR, AND THE TROUGH WALL BEING SHAPED SUBSTANTIALLY TO MATCH THE COMBINED CONTOUR OF THE HELICAL CONVEYORS. 